Traction-engine.



L BOLT.

TBACTION ENGINE.

APPLICATION FILED $113.13, 1913.

076,5?8 Pantea oct. 21, 1913.

2 SHEETS-SHEET 1.

B. HOLT.

TRACTON ENGINE.

APPLICATION FILED PBB.18,1913.

1,976,578. Patented 001121, 1913.

2 SHEETS-SHEET 2.

jig, s,

\VITXESS ICS: IN VENTOl Ee/gain n E02@ n I g* BY BEN'TAHE HOM, 0F SVIGCKTON, CALIFORNA.

TRACTN-ENGINE.

Specication of Letters Patent.

Patented (1ct. 21, i913.

Application filed February 18, 1913. Serial No. 749,168.

To all whom t may concern.'

Be it known that I, BENJAMIN HoLT, a citizen of the United States, residing at Stockton, in the county of San Joaquin and State of California, have invented new and useful Improvements in Traction-Engines, of which the following is a speciiication.

This invention relates to traction engines of the so-called caterpillar type, employing an endless, iexible traction member, or self-laying' track.

The ob]ect of the present invention is to materially reduce the size of these machines as compared with those I hara heretofore been building, and to simplify construction and reduce the number of perm in thetransmission, so as to deliver the power from the motor as directly as possible te the traction members; also to provide for the mounting for the truck or trucks which run on the ground run of the traction members so as to permit the trucks to rock and give the desired cushioning action to the load without the use of sprlngs, or the like.

There are other objects and advantages which will appear hereinafter.

The invention consists of the parts and the combination and construction of parts as hereinafter more `fully described and claimed, having reference to the accompanyinc drawings, in whieh igure l is a side elevation of the invention. Fi 2 is a cross section on line X X, Fig. 1. ig. 3 is a plan of the invention.

The engine frame, which may be of any suitable construction, referably comprises two main longitudinai) lrbeams or sills 2, rigidly connected across at intervals by upper and lower cross-pieces 3 4, which latter project somewhat beyond the sides of the sills 2. The projecting ends of the crosspic'ces 3 4 are connected by channels 5 to form lateral supplemental frames, but integral with the main frame for the accommodation of the rocking trucks 6, which have rollers 7 adapted to run on the ground run of the traction members 8. These traction members 8 support the chief weight of the vehicle.

9 is a front steering wheel having a connecting rod l0 which is suitably connected with the tiller wheel 11 adjacent to the drivcrs seat 12, at the rear of the vehicle.

13 is the motor by which power is transmitted back by suitable connections later to be described, for operating the traction members 8.

Each traction member consists of a series of conjoint links adapted to travel around front and rear sprockets 14 15, suitably )ournaled in line in the supplemental side frames. Front sprocket 14 is an idler, while the rear sprocket 15 is the driver.

Each truck 6 is mounted between a pair of respective sprockets 14f 15, and is of such strength and rigidity as to provide in itself an miiexible, unyielding beam, against which the back of the ground run of the traction members 8 may bear. The back of the traction members forms trackways in the nature of continuous rails for the rollers 7 for truck 6 to run u on. The trucks 6 are each centrally vand directly pivoted by a shaft 16 in the side frames 2 5, so that the truck has a limited rocking movement in a vertical plane about its shaft 16 as a fulcrum; all springs being dispensed with. The truck 6 is disposed between and inde pendent of the sprockets M l, and the underside of the rollers 7 project a suicient distance below the lowest points of the sprockets 14- 15 so that these sprockets, or rather those portions of the tract-ion member which are in immediate engagement with the sprockets, never come in contact with the ground. In other words, the entire weight of the vehicle, except what is carried on the steering wheel 9, 1s supported directl on the rocking trucks 6, independent o the sprockets lll- 15.

Practice shows that this construction allows the iexible, endless traction member to accommodate itself to rocks, or other inequalities in the roadway encountered, with' out the traction member bucklin u ward, or without any material or obJectlonnble vibration being imparted to the vehicle frame.

The direct pivoting of the trucks on the frame in the manner shown has been found in practical operation to give the necessary cushioning action to the vehicle, and without the interposition of any springs.

The front idlers 14 are journaled on independent shafts 17 mounted in sliding boxes 18, which engage lthe lower flanges of the pair .of side beams 2 5. The take-up of slack in the tread belts is provided for by push rods 19 which have one end bearing against a sliding box 18, and the other end threaded into a sleeve fast on the vehicle frame.

Each truck 6 by reason of the foregoing described mounting, has a limited oscillating movement about its fixed fulcrum 167 wholly independent of the sprocket wheels 14-15. As the operative face of each truck is normally in a plane below the level of the lowest point of the wheels 1st-15, the truck is guided in line and permited to oscillate in a vertical plane freely about its pivot 16; the spaces between the wheels 14.--15 and the slack of the belt being sufiicient Vto allow the truckand the portion of the. belt on which it rests to rock in unison; the truck being rigid and of sufficient length to be supported always on a plurality of links making up the belt so that there is no tendency of the ground run in the latter to undulate and thereby form an uneven, humpy track as the machine travels over it. By this truck construction whereby the pivot shafts 16 are comparatively` short and contained within the width of the belt and of the side frame, I am enabled to put the trucks quite low and to support the load directly on the trucks. Another feature which conduces to a low-hung frame lies in the construction and operation of the drive sprockets 15. Each of these drive sprockets has an internal gear 21 engaged by a pinion 22 fixed on the end of a drive shaft 23 which extends clear across the machine bet-Ween sprockets 15. The driving sprockets 15 for each traction member has its own independent short shaft 24, the ends of which are journaled in the supplemental side frames 2 5; there being no direct connections between the sprockets 15 on opposite sides of the machine eXcept through the driving shaft 23.

I find that by using short shafts 24 for each sprocket I am able to get a more compact and powerful construction than where it is attempted to mount both structures on one shaft and to interpose in this shaft a differential.

The drive shaft 23 carries two opposed normally loose master gears 2526. Either one of these gears 25-26 may be locked to shaft 23 by suitable respective clutch mechanism 27-28, according to whether the machine is to be driven ahead or in reverse. Power to operate the master gears 25-26 Vis derived from the motor 13 to asuitable transmission, generally indicated by the transmission shaft 29, which carries a pinion 30 adapted to be thrown in and out of mesh with one or the other of the', gears 25*QG, according as the transmission lshaft 29 is rocked in one direction or the other; a sliding bearing-31 operated by a clutch lever 32 being provided for the pinion end of the transmission shaft 29.

Clutches 27-28 are operated from the drivers seat by convenient means represented by the respective hand levers 33-34, as shown in the plan View Fig. 3.

36 is the lever for operating the engine clutch 35.

Having thus described my invention what I claim and desire to secure by Letters Patent is v The combination with a vehicle frame of front and rear sprockets supported in bearings on the frame and themselves supporting no part of the weight of the vehicle, an endless, flexible track belt passing around and guided by the sprockets, a truck traveling on the ground run of the belt and having an extended operative face normally in a plane below the level of the sprockets whereby the latter carry no part of the weight of the load7 said truck being centrally pivoted directly to the frame and capable of a limited rocking movement independent of the sprockets.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

BENJAMIN HOLT.

IVitnesses:

R. E. MANN, FRANKLIN S. HOLLEY.. 

